Curiously, no governor or junketing lieutenant governor has ever lifted a finger to promote the Evergreen State’s No. 2 agricultural cash crop. It’s because that crop — marijuana — is illegal, and various levels of government have spent billions of dollars in the “War on Drugs.” The war has seen the rout of its instigators.

A Hempfest pro-pot march: When marijuana was legalized in 2012, the cause was boosted by former U.S. attorneys, prosecutors and an FBI veteran. A lot of foes were at Hempfest.

“Evergreen: The Road to Legalization in Washington,” is an 86-minute documentary on how our voters finally decided it was time to exercise a modest use of intelligence. It follows the “New Approach Washington” campaign from its inception to passage of Initiative 502, which made Washington one of the first two states (Colorado is the other) to legalize, regulate and tax the weed.

“Evergreen” is featured at the Seattle International Film Festival and will be shown Thursday night at 9:30 in the Egyptian Theatre and at noon Saturday in the SIFF Cinema Uptown.

The documentary is predictable in some ways, but still amusing.

We see ancient film of federal drug boss Harry Anslinger spouting nonsense, and President Nixon proclaiming drugs “public enemy No. 1.” Nancy Reagan delivers her “Just Say No” line while the Gipper looks stern and scolding while reciting his lines about America’s youth.

But the real story is how advocates for a new drug approach grew up, and how they outgrew the tie-dyed counterculture folk who ended up providing noisy and totally ineffectual opposition to Initiative 502. Meanwhile, the drug bureaucracy in Washington, D.C., kept its powder dry, doubtless anticipating a prolonged bureaucratic war against the rational policy that threatens its ability to waste and cause hurt.

In “Evergreen’s” funniest moment, during a confrontation at the 2012 Seattle Hempfest, a leather-lunged activist shouts that the Initiative 502 campaign was courting soccer moms. “I don’t think you have the support of the true cannabis community,” he cries. (Soccer moms were, in fact, the campaign’s prime target.)

These required icons will show buyers that the marijuana product they’ve just purchased was made in Washington. The feds want marijuana grown in Washington to stay in Washington.

A moment later, spying young volunteers working for I-502, the guy doubles down on his despair: “I think you have people in the booth who don’t even smoke marijuana.”

The documentary features too many talking heads, but some have revealing stuff to say. “We are the number one jailing nation on Earth,” declares Seattle City Attorney Pete Holmes. When he took office in 2010, Holmes discovered “hundreds” of pending marijuana possession cases: 59 percent of the defendants were African-American, compared to less than 8 percent of the city’s population. Holmes deep-sixed the prosecutions.

“Evergreen” features a dour journalist — Jonathan Martin of The Seattle Times — who hedges his prediction on whether I-502 would win. (It swept to victory with 55.7 percent of the vote.) Steve Sher, interviewing on KUOW Radio, asks questions that could not penetrate a sheet of tissue paper.

In contrast, there are the original, revealing, amusing observations from Dominic Holden, news editor at The Stranger and a former Hempfest boss, on how ex-lawmen and civic pillars became advocates for marijuana legalization. (Friends of Holden will note his inevitable attire, a much-worn World Wildlife Fund T-shirt with a faded panda.)

The I-502 opponents, drawn from the medical marijuana monopoly, come across as clumsy, loud and dishonest. They try to break up supporters’ events. They deliver wild predictions about DUI arrests under provisions of the proposed law. In short, they are a perfect foil: Being targeted by crazies made advocates for I-502 seem all the more safe and responsible.

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“Evergreen” goes on the road with TV travel guru Rick Steves, who put $350,000 of his own money as well as his mouth to work at the cause. A delightful moment shows Steves making the case for I-502 in Leavenworth at the Sleeping Lady conference center, with liberal matriarch (and I-502 benefactor) Harriet Bullitt listening attentively.

It’s an OK ending, but a map of I-502’s county-by-county results leaves an intriguing question unanswered.

I-502 swept King County with more than 60 percent of the vote. However, in a politically polarized Washington, marijuana legalization crossed the “Cascade Curtain” and swept to victory in places like Okanogan, Ferry and Chelan counties.

Was it the economics — a lot of pot gets grown in Okanogan County — or a libertarian privacy streak that smoked out pro-marijuana voters in rural Washington?

Steves, driving through the Cascades, muses: “We’re talking, ‘Keep the government out of my body, out of my home,’ and I love it.”

Will the “War on Drugs” now take the form of a “War on Washington State?”